Mission

To achieve marine and fresh water quality objectives that will safeguard the health and welfare of the community and meet various conservation goals, by planning for the provision of sewage facilities, intervention in the planning process and by enforcing the controls in the Water Pollution Control Ordinance.

Stonecutters Island Sewage Treatment Plant has helped to improve water quality in the eastern harbour
Stonecutters Island Sewage Treatment Plant has helped to improve water quality in the eastern harbour
Anyone looking for good news about Hong Kong's marine water quality finally got something to cheer about in 2002. After years of deterioration, setbacks and technical glitches, Victoria Harbour's waters are starting to improve. The first stage of a massive sewage project has resulted in dramatically cleaner water, especially in the eastern part of the harbour, during its first year of operation.

The good news is tempered with caution, however. Unless the rest of the sewage project is built, water quality cannot improve in the rest of the harbour. It will also be difficult to maintain the recent gains because of pressure from a growing population. The government is working on plans for coping with these sewage loads, but it needs public agreement and support on the best methods and acceptable costs of doing so. The future health of the harbour rests on reaching such a consensus.
Harbour Water Watch promotes a cleaner harbour
At the heart of the clean-up of Victoria Harbour is HATS - the Harbour Area Treatment Scheme. This is a long-term project to stop sewage being dumped untreated into the harbour. Until the first stage of HATS was commissioned in late 2001, the harbour was taking in some 1.7 million tonnes a day of untreated sewage. Much ridicule was heaped on the fact that the "Fragrant Harbour" was not living up to its name.

The first stage of HATS involves collecting sewage from Kowloon and the eastern part of Hong Kong Island, treating it on Stonecutters Island and discharging the treated effluent into the western part of the harbour. This accounts for 70 per cent of the sewage that was previously dumped untreated. After one full year of operation, the improvements have been dramatic. The decline in water quality has not only been stopped, it has been reversed in most of the harbour.

Water Quality Improvements after Commissioning of HATS Stage I

Map showing changes in dissolved oxygen (mg/L), NH4(mg/L) and E.coli bacteria (cfu/100mL) at 17 stations in the HATS enhanced monitoring programme between (Jan - Dec 2002 ) and (Jan - Dec 2001)

Water quality is monitored regularly
Dissolved oxygen, which is needed to support marine life, has increased by 20 per cent in the eastern harbour. Ammonia, which is harmful to water quality, has dropped by 50-60 per cent. Bacteria linked to raw sewage has also dropped significantly in the eastern harbour. Similar improvements are expected in the western harbour once the scheme is extended to the rest of Hong Kong Island - although a question mark hangs over when that will happen.

The rest of HATS is now on hold, pending the outcome of three studies and a public consultation on its future form. In fact, it has been on hold for several years because of a lack of public consensus. The original strategy, unveiled in 1989, involved collecting, treating and discharging sewage from around the harbour by long outfall into the South China Sea. Initially, it had public support. But over the years, green groups, academics and others raised concerns that the proposed level of treatment and use of a long outfall would be inappropriate. At the same time, the technology was improving and a higher level of treatment was becoming more practicable. This kind of treatment also required less land.

Testing Water Quality

Traditional ways of monitoring water quality involve looking at the physical and chemical characteristics of the water and using this to predict the health of biological communities. But there is a move internationally to look at the biological impacts directly, so as to get more accurate information about the effects of pollution. For example, biological indicators can show if the number of species is dropping or if the variety of creatures within one species has fallen. Biological indicators can also show such things as whether marine animals are healthy, their DNA has changed or their growth rate has altered.

Hong Kong has used biological indicators to assess water quality around the contaminated mud dumping site at East Sha Chau and the toxicity in sediment. A study is underway to examine how this could be extended to water quality monitoring in general, so the public and decision-makers can have a clearer idea of the impacts of pollution. Biological indicators would supplement the physical and chemical tests, and also help us to understand better the effectiveness of these tests.
Microscopic organisms can be picked up in water samples

Fish can become diseased from swimming in polluted waters

Biological Aerated Filter

A Biological Aerated Filter at close range
Biological Aerated Filter (BAF) is the core element of a compact sewage treatment process that can produce a very high quality effluent. The "filter" is in fact made up of granular material which has a large surface area for growing certain bacteria. The material and the attached bacteria are packed into a reactor through which sewage flows. The actions of the bacteria "filter" the sewage and break down the waste. The bacteria are fed a vigorous stream of air through air nozzles at the bottom of the reactor, which helps them to work quickly. Thus, the combination of the air and the filtering action of the bacteria have led to the term "Biological Aerated Filter".

In a conventional biological treatment process, it is necessary to place large sedimentation tanks after the main reaction tanks, to allow the bacteria to settle out as sludge so that it would not be discharged together with the treated wastewater. BAF skips this step because the bacteria are held in the filter. It therefore takes up much less space than a plant adopting a more conventional process.

The lack of consensus in the community led the Chief Executive, Mr Tung Chee-hwa, to announce in 1999 that an International Review Panel of experts would study the scheme and propose options. The panel's report, released in late 2000, recommended a new compact treatment technology which could provide a higher level of treatment and enable effluent to be discharged into Victoria Harbour. It suggested the government investigate four options based on this concept to address demands from the community.

In the wake of the report, the government has undertaken a major study into the environmental and engineering feasibility, including costs, of the various options. A second study is testing the effectiveness of the recommended biological aerated filter technology, and other technologies, in Hong Kong's hot climate. And a third study, initiated in 2002, is looking at whether private sector participation in sewage treatment could be more cost-effective and efficient.

The three studies will be completed in 2003. By the end of the year, the government hopes it will have the information needed to start consulting the public on the best sewage treatment option for the harbour. Consensus-building is a top priority. Just as important will be the need to convince people that Victoria Harbour, Hong Kong's "green lung", is worth protecting from further deterioration. In 2002, the government started highlighting the value and importance of the harbour at carnivals and other dealings with the public, and on a dedicated HATS website. More of this awareness raising will be carried out in the coming year.
Kai Tak nullah's odour problem arose from poor planning
An unfortunate fact about HATS is that much of it is essentially a catch-up exercise. The treatment plants are being put in place long after millions of people started discharging their sewage into the harbour. Like many other developed cities, Hong Kong wants to prevent problems like this from arising in future. The best way is to plan against water pollution and prevent further deterioration of the harbour, rivers and other water bodies.

A small but characteristic example of poor planning is Kai Tak nullah, at the end of which is a typhoon shelter. The nullah and typhoon shelter were built before proper planning controls were introduced. The nullah is bordered by the runway path of the old airport on one side, and Kwun Tong on the other. Kwun Tong is an old industrial area. When it rains, the rainwater will carry with it all the pollution matters from the streets and pavements and discharge them into the nullah where they will be trapped. The smell from the contaminated waters can be overwhelming and it will take a lot of expensive engineering work to correct it.

Grease Trap Waste

Restaurants and the food industry produce large amounts of oil and grease. If this is tipped down drains it can quickly clog sewers, leading to an overflow of sewage. To control the problem, the level of grease and oil allowed in effluent from these establishments has been capped under the Water Pollution Control Ordinance. Grease traps are the cheapest way of meeting the requirement. These can be installed under sinks or in drains, and contractors can skim the grease off the top.

The EPD has used enforcement and a partnership approach with restaurants to encourage co-operation in controlling this potential water pollution problem. The results have been positive. Levels of waste brought to a special grease trap waste facility at the West New Territories landfill have increased steadily since it opened five years ago.
A grease trap waste treatment facility at WENT landfill
Grease trap waste should not go down the drain

Silt curtains help to contain the impacts from dredging and dumping at sea
The Environmental Protection Department (EPD) is trying to make situations like Kai Tak nullah a thing of the past, by giving input early in the planning stage. On one level, it looks at individual projects. The Environmental Impact Assessment Ordinance is used to assess impacts, including construction work, of these projects and advise on whether they are environmentally acceptable. Mitigation measures can be stipulated if necessary, for example, requiring dredgers to use silt curtains so they do not damage coral sites or marine life when marine works are carried out.

On another level, the department scrutinises major development proposals for their impacts, such as reclamations. Proposed reclamations have to be designed so they do not constrict the flow of major tidal channels. The layout of the reclamation at Chek Lap Kok airport was changed to an island after it was predicted that attaching it to Lantau would severely restrict water flow.
Victoria Harbour is Hong Kong's most prominent natural asset
Projects like HATS also come under major development proposals. The EPD tries to ensure there are enough sewers and treatment plants in place to cope with any predicted increase in population. The population around Victoria Harbour is expected to increase to 6.3 million under a full development scenario. The system that is chosen under HATS will not only have to deal with past and present water pollution, but also cope with future sewage loads.
The EPD regularly publishes its results on water quality
The community has supported the government's efforts to plan against water pollution. It must also support its efforts to deal with the pollution that is created nonetheless. Sewage is unavoidable and cannot be prevented outright. But dealing with sewage is expensive and the community must decide on the financial and environmental costs it is willing to pay for cleaning up the harbour.

Some people might want a high level of treatment, to the extent that the effluent could be re-used in such things as gardening and flushing. The cable car development at Ngong Ping will test this level of treatment when it starts operating in 2005. Others might want a cheaper solution, which would involve a lower grade of treatment and may have residual environmental impacts.

In any case, a value must be put on Victoria Harbour. It helps to remember that the harbour is part of Hong Kong's heritage. People used to swim and fish there not so long ago. A vibrant shipping industry still operates there. More symbolically, Victoria Harbour is part of the popular image of Hong Kong, of skyscrapers rising from blue waters against a backdrop of green hills. It is one of the few public places in Hong Kong with wide open views. Victoria Harbour should be treasured. The community must think of it in these terms if it is to reach a consensus on how to protect our best natural asset.

Effluent Re-use

The treatment of sewage creates a possible resource. If treated to a high enough level, the treated effluent can be re-used in many ways. For example, if it meets public health standards it can be used for flushing, landscape irrigation, cooling in plants or cleaning vehicles - rather than using potable water. Other countries have done this and found it saves on water resources and reduces the load on sewage plants.

Hong Kong's first trial using treated effluent will be carried out at the cable car development at Ngong Ping on Lantau Island. Tertiary-level treatment followed by disinfection will be applied to sewage generated at the site and the treated effluent will be used for flushing and controlled irrigation. If the trial is successful, treated effluent re-use may be considered for other parts of Hong Kong as an alternative to potable water, for example for flushing purposes in North District and Tolo Harbour. Construction of the Ngong Ping sewage works will start in 2003 and be completed by August 2005.


Location of Ngong Ping sewage treatment work
Treated and disinfected effluent can be re-used in such things as flushing, landscape irrigation and vehicle cleaning

Highlights of 2002
• Participated in the First APEC Ocean-related Ministerial Meeting.
• Presented a well-received paper to the 25th Scientific Group Meeting of the London Dumping Convention on the monitoring results of the East Sha Chau contaminated mud disposal site.
• Finalised with Guangdong the technical requirements of the Pearl River Delta Water Quality Model and appointed the Project Co-ordinator.
• Started a regular information exchange on Deep Bay's water pollution control programmes with Shenzhen.

Looking Ahead
• Complete the ongoing sewerage master plan reviews which take account of sewerage needs arising from a growing population.
• Commence an effluent reuse demonstration scheme in North District.
• Complete the HATS studies by November 2003, and forge a consensus in the community on the way forward.
• Formulate a water quality management plan for Mirs Bay jointly with Shenzhen.

• Develop a biological indicator system for monitoring marine pollution in Hong Kong.
• Develop proposals for an appropriate toxic substances control strategy.